V-Control Pro will connect to the first DAW that it detects and can only connect to one DAW at a time. If running multiple applications and you wish to connect to a specific application, quit all other applications so only V-Control Pro and the app you wish to connect to are open.
For example, if wanting to connect to Pro Tools but you also have an application such as TotalMix running, V-Control Pro will detect TotalMix and connect and will not then connect to Pro tools.
Quit TotalMix to allow Pro Tools to connect, then you can relaunch TotalMix.